The Perfect Bacon Sandwich Decoded: Crisp and Crunchy

LONDON, April 10 — Should it be slithery or scrunchy, glutinous or grilled? The answer, British scientists say, may be divined by a formula: N = C + {fb(cm) · fb(tc)} + fb(Ts) + fc · ta.

That is the scientific answer to the question: what makes the perfect bacon sandwich?

And, no, it is not April 1.

Researchers at Leeds University spent more than 1,000 hours testing 700 variants on the traditional bacon sandwich, which many Britons refer to as a bacon butty (eschewing the term sandwich, said to have been coined to honor the fourth Earl of Sandwich’s habit of eating meat between slices of bread around 1762).

For Britons, butties come in a variety of guises — chip butties (French fries between slices of bread), crisp butties (ditto with potato chips) or even sugar butties, which are self-explanatory. None are viewed as especially healthful.

There are some finer points in the language, if not the cuisine. A sandwich containing sausages, for instance, is likely to be referred as a sausage sarnie, while sausages served with mashed potatoes are called bangers and mash.

Even the bacon butty, though alliterative, is sometimes etymologically challenged, as in a recent posting on the Web site of The Yorkshire Post relating to the study at Leeds University.

“Perhaps another few minutes on research would have told them that a butty is a slice of buttered bread with a topping; a bacon sarnie is what they are describing,” said a contributor who signed himself Joey Pica.

But Graham Clayton, who led the research, said the endeavor had been an earnest attempt, commissioned by the Danish Bacon and Food Council, the British subsidiary of a Danish pig producers’ organization, to determine what degree of crispiness and crunchiness made the perfect sandwich.

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Researchers at Leeds University found that crisp bacon on white bread makes the perfect bacon sandwich.

The company’s announcement of the research last Sunday made no reference to other criteria like cholesterol, carbohydrates or other dietary attributes of the perfect butty. Chloe Joint, a spokeswoman for Danish Bacon’s public relations company, Porter Novelli, declined to say how much the study cost.

The research combined four types of cooking, using grills, pans and ovens, three kinds of oil and four types of bacon — smoked, unsmoked, streaky and thick cut — to establish the preferences of 50 tasters in such matters as the butty’s tactile and aural crunchiness. The study also considered a broad range of condiments (like ketchup and brown sauce) and spreads.

It concluded that the best bacon butties were made with crisply grilled, not-too-fat bacon between thick slices of white bread.

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“We often think that it’s the taste and smell of bacon that consumers find most attractive,” Dr. Clayton said in a news release. “But our research proves that texture and sound is just, if not more, important.”

In a telephone interview, he also acknowledged that tasters made comments about fat. “If there was too much fat from the cooking process, that was a turnoff for people,” he said. Leathery bacon was a no-no, too, he added.

“We are programmed to avoid leathery food as old and not very good,” he said. That wisdom does not seem to prevail, however, among some of the more basic vendors of bacon butties at roadside halts or cafes known generically as greasy spoons to denote their customary modes of cooking and hygiene.

In the experiment, some of the tasters sampled between four and six bacon sandwiches a day for three or four days.

And so the formula evolved to establish the amount of force in the bite, expressed in newtons, and the level of noise, expressed in decibels, to make the perfect crunch.

Ideally, Danish Bacon said, 0.4 newtons should be applied to crunch the sandwich, creating 0.5 decibels of noise. The formula uses these values: N = force in newtons; fb is the function of the bacon type; fc is the function of the condiment or filling effect; Ts is the serving temperature; tc is cooking time; ta is the time taken to insert the condiment or filling; cm is the cooking method and C represents the breaking strain in newtons of uncooked bacon.

“It’s not a hoax,” Dr. Clayton said, acknowledging that, a few days ago — on April 1, to be precise — it might have been taken as one.

A version of this article appears in print on , on Page A4 of the New York edition with the headline: The Perfect Bacon Sandwich Decoded: Crisp and Crunchy. Order Reprints|Today's Paper|Subscribe